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91.
We have shown that cystic fibrosis transmembrane conductance regulator (CFTR) is involved in ATP release from skeletal muscle at low pH. These experiments investigate the signal transduction mechanism linking pH depression to CFTR activation and ATP release, and evaluate whether CFTR is involved in ATP release from contracting muscle. Lactic acid treatment elevated interstitial ATP of buffer-perfused muscle and extracellular ATP of L6 myocytes: this ATP release was abolished by the non-specific CFTR inhibitor, glibenclamide, or the specific CFTR inhibitor, CFTRinh-172, suggesting that CFTR was involved, and by inhibition of lactic acid entry to cells, indicating that intracellular pH depression was required. Muscle contractions significantly elevated interstitial ATP, but CFTRinh-172 abolished the increase. The cAMP/PKA pathway was involved in the signal transduction pathway for CFTR-regulated ATP release from muscle: forskolin increased CFTR phosphorylation and stimulated ATP release from muscle or myocytes; lactic acid increased intracellular cAMP, pCREB and PKA activity, whereas IBMX enhanced ATP release from myocytes. Inhibition of PKA with KT5720 abolished lactic-acid- or contraction-induced ATP release from muscle. Inhibition of either the Na+/H+-exchanger (NHE) with amiloride or the Na+/Ca2+-exchanger (NCX) with SN6 or KB-R7943 abolished lactic-acid- or contraction-induced release of ATP from muscle, suggesting that these exchange proteins may be involved in the activation of CFTR. Our data suggest that CFTR-regulated release contributes to ATP release from contracting muscle in vivo, and that cAMP and PKA are involved in the activation of CFTR during muscle contractions or acidosis; NHE and NCX may be involved in the signal transduction pathway. 相似文献
92.
Numts are an integral component of many eukaryote genomes offering a snapshot of the evolutionary process that led from the incorporation of an α-proteobacterium into a larger eukaryotic cell some 1.8 billion years ago. Although numt sequence can be harnessed as molecular marker, these sequences often remain unidentified and are mistaken for genuine mtDNA leading to erroneous interpretation of mtDNA data sets. It is therefore indispensable that during the process of amplifying and sequencing mitochondrial genes, preventive measures are taken to ensure the exclusion of numts to guarantee the recovery of genuine mtDNA. This applies to mtDNA analyses in general but especially to studies where mtDNAs are sequenced de novo as the launch pad for subsequent mtDNA-based research. By using a combination of dilution series and nested rolling circle amplification (RCA), we present a novel strategy to selectively amplify mtDNA and exclude the amplification of numt sequence. We have successfully applied this strategy to de novo sequence the mtDNA of the Black Field Cricket Teleogryllus commodus, a species known to contain numts. Aligning our assembled sequence to the reference genome of Teleogryllus emma (GenBank EU557269.1) led to the identification of a numt sequence in the reference sequence. This unexpected result further highlights the need of a reliable and accessible strategy to eliminate this source of error. 相似文献
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Harvey E. Ballard Dale A. Casamatta Melissa M. Hall Ross A. McCauley Maria Claudia Segovia-Salcedo Robert G. Verb 《Brittonia》2001,53(1):122-136
Phenetic investigations were undertaken to evaluate differences between the cloud forest endemicViola domingensis of the Dominican Republic and the morphologically similarV. macloskeyi of continental North America. Cluster, principal components (PCA), and canonical variates analyses (CVA) of leaf characters
and of ratios derived from them consistently separateV. macloskeyi subsp.macloskeyi of the Pacific states fromV. domingensis and transcontinentalV. macloskeyi subsp.pallens. However, all analyses portray the latter two as extensively intergradient extremes of a continuum, withV. domingensis plants tending to be smaller. Phenetic analyses of capsule and seed features, which are often divergent among other species
of subsect.Stolonosae, showV. domingensis to be nested within a broaderV. macloskeyi subsp.pallens. Similarly, floral morphology does not provide observable differences between the pair. Results support the synonymy ofV. domingensis underV. macloskeyi subsp.pallens and reveal that it represents a disjunct outlier of an otherwise continental North American violet. 相似文献
95.
The effect of eccentric contraction on force generation and intracellular pH (pH(i)) regulation was investigated in rat soleus muscle. Eccentric muscle damage was induced by stretching muscle bundles by 30% of the optimal length for a series of 10 tetani. After eccentric contractions, there was reduction in force at all stimulation frequencies and a greater reduction in relative force at low-stimulus frequencies. There was also a shift of optimal length to longer lengths. pH(i) was measured with a pH-sensitive probe, 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein AM. pH(i) regulation was studied by inducing an acute acid load with the removal of 20-40 mM ammonium chloride, and the rate of pH(i) recovery was monitored. The acid extrusion rate was obtained by multiplying the rate of pH(i) recovery by the buffering power. The resting pH(i) after eccentric contractions was more acidic, and the rate of recovery from acid load post-eccentric contractions was slower than that from postisometric controls. This is further supported by the slower acid extrusion rate. Amiloride slowed the recovery from an acid load in control experiments. Because the Na(+)/H(+) exchanger is the dominant mechanism for the recovery of pH(i), this suggests that the impairment in the ability of the muscle to regulate pH(i) after eccentric contractions is caused by decreased activity of the Na(+)/H(+) exchanger. 相似文献
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Maureen Tuffrey D. Abeck Frances Alexander A.P. Johnson R.C. Ballard D. Taylor-Robinson 《FEMS microbiology letters》1988,50(2-3):207-209
Abstract Six- to 8-week-old CBA mice were inoculated intradermally and/or subcutaneously on each flank with one of 3 strains of Haemophilus ducreyi , 2 of these being recent isolates and the other a reference strain. Pustular nodules developed at all sites the day after 107 organisms had been given. Severe ulceration similar to chancroid occurred in about half of the lesions which took at least 13 days to heal. All three strains of H. ducreyi were isolated from the mice during the first week. The model is invaluable in helping to understand the pathogenicity of H. ducreyi as well as the immunopathogenesis and other aspects of chancroid. 相似文献
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